Taste is a critical sensory system for food selection and ingestion. Results obtained during the current funding period have provided intriguing new findings about how temperature is a stimulus for specific types of gustatory neurons, how sodium deprivation increase the salience of salt intake, and about behavioral responses to the taste of fat. The long-term objectives of this proposal are to investigate: (1) temperature- processing mechanisms in peripheral taste neurons and taste-temperature interaction in behavioral studies;(2) the role of aldosterone and body sodium levels as mediators for deprivation-induced changes in salt taste nerve responses;and (3) sensory processing of fat taste and the modulation of other taste stimuli by fat. These are significant unanswered questions in the field of chemosensory research that follow logically from our previous work and that will be addressed with electrophysiological and behavioral methodology developed explicitly for the purposes outlined above. The specific aims include investigating whether taste and thermal stimulation have additive effects in specific types of peripheral taste neurons and whether thermal stimulation itself elicits taste sensations in rats. We will also determine whether the TRPM8 channel is the mechanism that mediates responses to cooling in taste neurons. We also propose to investigate the effect of brief dietary sodium deprivation on taste nerve responsiveness to salt stimulation, the mechanism(s) that underlie such changes, and whether repletion of body sodium levels restores taste nerve responsiveness. Finally, we will explore taste nerve responses to fat alone and in combination with other taste stimuli, and will conduct studies to evaluate the contribution of gustatory nerves to the detection of fat taste and fat taste-mediated behaviors. Overall, this project will use single-cell and whole nerve recording to illuminate information processing of temperature, salt, and fat in peripheral taste neurons and behavioral methods to help solve the mystery of how these important stimuli mediate changes in behavior.